/Engine/Source/Editor/UnrealEd/Public/EditorLevelUtils.h
Adds the named level packages to the world. Does nothing if all the levels already exist in the world.
The new level, or NULL if the level couldn't added.
static [ULevel](API\Runtime\Engine\Engine\ULevel) * AddLevelsToWorld ( [UWorld](API\Runtime\Engine\Engine\UWorld) * InWorld, [TArray](API\Runtime\Core\Containers\TArray)< [FString](API\Runtime\Core\Containers\FString) > LevelPackageNames, [TSubclassOf](API\Runtime\CoreUObject\Templates\TSubclassOf)< [ULevelStreaming](API\Runtime\Engine\Engine\ULevelStreaming) > LevelStreamingClass )